SC comparison/idioms

[gkhan]

Scientists have created a new substance that is [img]so%20transparent%20as%20to%20be[/img] almost invisible.

A. so transparent as to be
B. so transparent it has been
C. so transparent that it was
D. transparent enough so that it is
E. transparent enough so as to be

I went with D because MGMAT's SC (4th Ed./Ch.9) claims the grammatical construction of "so" + "that" = purpose.

Can someone provide a reason for D's incorrectness? Below is my thought pattern:

A. "so...as to" okay but "so... as TO BE" not likely for GMAC to accept because of comparison has only one infinitive on the latter, also sounds like it doesn't abide by any parallelism
B. "have created" vs "has created" plural/singular also no clear cut order
C. "so...was" bad idiom
D. I liked
E. again the "so...as to be" threw me off.

Answer: A

[Ben Ku]

Notice that there are several constructions that involve "So" and "That."

Type 1: The expression "so X that Y" describes that Y happens because of X. In this idiom, "so" and "that" must be sandwiched around a description.
I was so happy with my score that I bought ice cream to celebrate.

Type 2: The expression you're referring to "X so that Y" means the PURPOSE of X is Y. In this idiom, "so that" must be kept together.
I gave Sue five dollars so that she could buy a sandwich.

The incorrect answer choice (D) uses Type 2, because "so that" is not split. However, the purpose of creating the new substance is NOT to be invisible.

This sentence actually means that this new substance has the property of being almost invisible.

[gkhan]

Notice that there are several constructions that involve "So" and "That."

Type 1: The expression "so X that Y" describes that Y happens because of X. In this idiom, "so" and "that" must be sandwiched around a description.
I was so happy with my score that I bought ice cream to celebrate.

Type 2: The expression you're referring to "X so that Y" means the PURPOSE of X is Y. In this idiom, "so that" must be kept together.
I gave Sue five dollars so that she could buy a sandwich.

The incorrect answer choice (D) uses Type 2, because "so that" is not split. However, the purpose of creating the new substance is NOT to be invisible.

This sentence actually means that this new substance has the property of being almost invisible.

Thanks Ben.

[Ben Ku]

You're welcome!

[NehaM981]

hii

Why d is incorrect ??

Thanks
Neha